This invention relates to a seal assembly for endless tracks used for construction vehicles and mining machines such as bulldozers, dozer shovels and power shovels etc.,
A seal assembly of this kind which has heretofore been employed comprises as shown in FIGS. 1 and 2, a W-shaped seal member "d" and a spacer "e" disposed within a counterbore wall "c" defined by a bush "a" and a link "b". Such sealing assembly is disadvantageous in that since earth and sand enter sometimes into "A" part, bush "a" tends to move in the direction of thrust and can not return accurately to its original position, and the seal member "d" tends to fall or move sidewards in the direction shown by an arrow in FIG. 2. Further, regarding the distribution of pressures "B" acting on the seal member "d", it is high in the inner peripheral portion and low in the outer peripheral portion, and a great deal of earth and sand tend to enter thereinto from the outer peripheral portion.
Another seal assembly is disclosed in U.S. Pat. No. 3,841,718 which comprises as shown in FIGS. 3 and 5 a seal member "d" having a lip "f" formed therewith. However, this type of seal assembly is disadvantageous in that it is difficult to assemble because of its lip type of seal; the lip "F" tends to fall or move sidewards in the direction shown by an arrow in FIG. 4; the lip extends inwardly as shown by broken lines in FIG. 3 when it is assembled so that it is necessary to provide a considerable clearance "l"; and a groove is formed in the face "g" of the lip "f" which contacts with the end face of the bush "a", thereby reducing the durability of the seal.
When foreign matters such as earth and sand etc. enter in between the bush "a" and the contact face "g" of the lip "f" as shown in FIG. 5, because of a narrow width of the contact face "g" of the lip "f", the contact face "g" becomes rough or the lip "f" per se is damaged thus causing oil leaks and reducing the sealing effect of the seal assembly.